nongnu: firefox-esr: Support Guix icecat browser extensions.

* nongnu/packages/patches/firefox-esr-compare-paths.patch: New file.
* nongnu/packages/patches/firefox-esr-use-system-wide-dir.patch: New file.
* nongnu/packages/mozilla.scm (firefox-esr)[source]: Add them.
[arguments]<#:configure-flags>: Allow unsigned system addons.
[native-search-paths]: Add ICECAT_SYSTEM_DIR.

nongnu/packages/mozilla.scm

@@ -98,7 +98,15 @@
        (uri (string-append "https://archive.mozilla.org/pub/firefox/releases/"
                            version "/source/firefox-" version ".source.tar.xz"))
        (sha256
-        (base32 "1awl0yhcv693q23p6zw9rw40gicpp6pakbx616qsl5w85d2arijz"))))
+        (base32 "1awl0yhcv693q23p6zw9rw40gicpp6pakbx616qsl5w85d2arijz"))
+       (patches
+        (map (lambda (patch)
+               (search-path
+                (map (cut string-append <> "/nongnu/packages/patches")
+                     %load-path)
+                patch))
+             '("firefox-esr-compare-paths.patch"
+               "firefox-esr-use-system-wide-dir.patch")))))
     (build-system gnu-build-system)
     (arguments
      (list
@@ -130,6 +138,11 @@
             "--with-distribution-id=org.nonguix"
             "--disable-official-branding"
 
+            ;; Do not require addons in the global app or system directories to
+            ;; be signed by Mozilla.
+            "--allow-addon-sideload"
+            "--with-unsigned-addon-scopes=app,system"
+
             ;; Features
             "--disable-tests"
             "--disable-updater"
@@ -482,6 +495,11 @@
         rust-cbindgen-0.26
         which
         yasm))
+    (native-search-paths
+     (list (search-path-specification
+            (variable "ICECAT_SYSTEM_DIR")
+            (separator #f)              ;single entry
+            (files '("lib/icecat")))))
     (home-page "https://mozilla.org/firefox/")
     (synopsis "Trademarkless version of Firefox")
     (description

nongnu/packages/patches/firefox-esr-compare-paths.patch

@@ -0,0 +1,23 @@
+See comment in gnu/build/icecat-extension.scm.
+
+diff --git a/toolkit/mozapps/extensions/internal/XPIDatabase.sys.mjs b/toolkit/mozapps/extensions/internal/XPIDatabase.sys.mjs
+index 0b885f6..0bbfbee 100644
+--- a/toolkit/mozapps/extensions/internal/XPIDatabase.sys.mjs
++++ b/toolkit/mozapps/extensions/internal/XPIDatabase.sys.mjs
+@@ -3607,6 +3607,7 @@ export const XPIDatabaseReconcile = {
+     if (
+       newAddon ||
+       oldAddon.updateDate != xpiState.mtime ||
++      oldAddon.path != xpiState.path ||
+       (aUpdateCompatibility && this.isAppBundledLocation(installLocation))
+     ) {
+       newAddon = this.updateMetadata(
+@@ -3615,8 +3616,6 @@ export const XPIDatabaseReconcile = {
+         xpiState,
+         newAddon
+       );
+-    } else if (oldAddon.path != xpiState.path) {
+-      newAddon = this.updatePath(installLocation, oldAddon, xpiState);
+     } else if (aUpdateCompatibility || aSchemaChange) {
+       newAddon = this.updateCompatibility(
+         installLocation,

nongnu/packages/patches/firefox-esr-use-system-wide-dir.patch

@@ -0,0 +1,38 @@
+Replace "/usr/lib/mozilla" (the system-wide directory for extensions and
+native manifests) with "$ICECAT_SYSTEM_DIR".
+
+diff --git a/toolkit/xre/nsXREDirProvider.cpp b/toolkit/xre/nsXREDirProvider.cpp
+index d3af49b495..4beef0aa7e 100644
+--- a/toolkit/xre/nsXREDirProvider.cpp
++++ b/toolkit/xre/nsXREDirProvider.cpp
+@@ -296,24 +296,12 @@ nsresult nsXREDirProvider::GetBackgroundTasksProfilesRootDir(
+ static nsresult GetSystemParentDirectory(nsIFile** aFile) {
+   nsresult rv;
+   nsCOMPtr<nsIFile> localDir;
+-#  if defined(XP_MACOSX)
+-  rv = GetOSXFolderType(kOnSystemDisk, kApplicationSupportFolderType,
+-                        getter_AddRefs(localDir));
+-  if (NS_SUCCEEDED(rv)) {
+-    rv = localDir->AppendNative("Mozilla"_ns);
+-  }
+-#  else
+-  constexpr auto dirname =
+-#    ifdef HAVE_USR_LIB64_DIR
+-      "/usr/lib64/mozilla"_ns
+-#    elif defined(__OpenBSD__) || defined(__FreeBSD__)
+-      "/usr/local/lib/mozilla"_ns
+-#    else
+-      "/usr/lib/mozilla"_ns
+-#    endif
+-      ;
+-  rv = NS_NewNativeLocalFile(dirname, false, getter_AddRefs(localDir));
+-#  endif
++
++  const char* systemParentDir = getenv("ICECAT_SYSTEM_DIR");
++  if (!systemParentDir || !*systemParentDir) return NS_ERROR_FAILURE;
++
++  rv = NS_NewNativeLocalFile(nsDependentCString(systemParentDir), false,
++                             getter_AddRefs(localDir));
+ 
+   if (NS_SUCCEEDED(rv)) {
+     localDir.forget(aFile);